Delirium is a type of confusion that happens when the combined strain of illnesses, environmental circumstances or other risk factors disrupts your brain function. It’s more common in adults over 65. This condition is serious and can cause long-term or permanent problems, especially with delays in treatment. However, it’s also often preventable.


What is delirium?

Delirium is a fast-developing type of confusion that affects your ability to focus your attention and awareness. It happens when there’s widespread disruption in brain activity, usually because of a combination of factors. Delirium is more common in medical settings, such as during long hospital stays or in long-term care facilities.

People with delirium often act very differently than they do under ordinary circumstances. A common statement or feeling among people who see a loved one with delirium is, “That’s not the person I know.”

In years past, experts thought delirium was a relatively harmless and minor concern. Today, they know it’s a serious problem that should be recognized and prevented whenever possible.

How common is delirium?

Research indicates that delirium affects between 18% and 35% of people admitted to a hospital for inpatient care. Up to 60% of people in an intensive care unit may experience delirium. However, researchers suspect delirium is more common than statistics indicate. The available research suggests that between 1 in 3 and 2 in 3 delirium cases go undiagnosed.

While delirium is more common in older adults, especially those over 65, it can happen to anyone. That means children, teenagers and young adults can all develop it under the right circumstances.


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Is delirium the same as dementia?

Delirium and dementia aren’t the same thing. Delirium involves “waxing and waning” symptoms, meaning they get better and worse. Dementia refers to a steady decline in thinking ability.

However, it’s easy to think they’re the same because they have so many similarities. They can also overlap and happen at the same time, and having dementia increases your risk of developing delirium. Delirium can also accelerate your development of dementia or make existing dementia worse.

Both delirium and dementia involve confusion, but there are some important differences:

How rapidly does it appear?
Fast. It appears over hours or days.
Slowly. It can take years before it’s serious enough to notice.
What happens over time?
It can come and go, getting better or worse from hour to hour.
It gets slowly and progressively worse.
Is it preventable?
Yes, in up to one-third of cases.
Is it treatable?
Yes, especially with treatable causes.
No, but some symptoms are treatable.
Can it get better?
Yes, but recovery is less likely or will take longer without treatment.
No. Dementia is permanent.

What are some other terms for delirium?

One of the biggest reasons why delirium often goes unrecognized is because there’s a history of describing it using different terms or names. Today, healthcare providers use this term very specifically.

Other terms or phrases people use (or previously used) to describe delirium can include:

  • Sundowning.
  • Pleasantly confused.
  • Intensive care unit (ICU) or post-surgery psychosis.
  • Altered mental status (this term is useful in other contexts but isn’t preferred for delirium).
  • Encephalopathy.

Symptoms and Causes

What are the symptoms of delirium?

Delirium indicates a widespread disruption in brain activity. That means there are many possible symptoms of delirium. It’s also important to remember the symptoms may look different from one person to the next. It can also fluctuate. Delirium can often get better during the day and worse as nighttime approaches, which is why this condition sometimes gets the incorrect name of “sundowning.”

The main symptom of delirium is confusion. That means you have trouble with:

  • Focusing or shifting your attention when necessary.
  • Thinking and concentrating.
  • Remembering facts, events, people, etc.
  • Staying aware of your surroundings.
  • Answering correctly when asked what time it is, the date and where you are.
  • Trouble speaking clearly, answering questions or understanding what others are saying.
  • Trouble processing what you see, including identifying objects or where you are.
  • Feeling more emotional, scared or angry.

Symptom patterns of delirium tend to fall into one of three categories:

  • Hyperactive.
  • Hypoactive.
  • Mixed.

Hyperactive delirium

This type of delirium involves higher activity levels. It can include:

  • Agitation.
  • Aggression, combativeness or refusal to cooperate.
  • Mood swings.
  • Poor sleep during nighttime hours.
  • Psychosis symptoms, including delusions and hallucinations.
  • Loss of “filter,” such as using profanity in a way that’s not typical of you or saying things you wouldn’t ordinarily say.

Hypoactive delirium

This type of delirium involves lower activity levels. Hypoactive delirium is harder to diagnose because healthcare providers may mistake it for fatigue or depression. Symptoms include:

  • Reduced facial expressions and speaking.
  • Reduced responsiveness to changes in your environment.
  • Apathy and a lack of interest in what’s happening around you.
  • Sluggishness, slowed movements or lethargy.
  • Diminished interest or participation in your care.


As the name suggests, the mixed type of delirium combines features of the hyperactive and hypoactive types. It tends to have one of the following appearances:

  • Typical activity level: You’re still confused and not fully aware of your surroundings, but your activity level is similar to what’s usual for you.
  • Shifting activity level: You shift back and forth between the hyperactive and hypoactive delirium types. Sometimes you may show hyperactive symptoms but then change to hypoactive symptoms. This can also involve hypoactive symptoms and sleeping during the day, and hyperactive symptoms like agitation or aggression at night.


What causes delirium?

Available research indicates that delirium is a complex condition that doesn’t happen for a single reason. Instead, delirium occurs when the “balancing act” between your functional capacity, your functional limitations and other stressors gets pushed too far. On one side is your functional capacity. That’s how much you can handle and recover from without being overwhelmed. On the other side are stressors. That’s anything that makes it harder for your body to work as it should.

Functional capacity (+)
Physical health.
Functional limitations (-)
Chronic health conditions.
Stressors that can cause or contribute to delirium (-)
Acute (sudden) illnesses.
Mental health.
Functional limitations (-)
Mental health conditions.
Stressors that can cause or contribute to delirium (-)
New or chronic injuries.
Energy level.
Functional limitations (-)
Increasing age.
Stressors that can cause or contribute to delirium (-)
Medical procedures, surgeries or hospital stays.
Functional limitations (-)
Poor diet.
Stressors that can cause or contribute to delirium (-)
Functional limitations (-)
Trouble hearing or seeing what’s happening around you.
Stressors that can cause or contribute to delirium (-)
Lack of sleep.
Functional limitations (-)
Stressors that can cause or contribute to delirium (-)
Lack of mobility.
Functional limitations (-)
Stressors that can cause or contribute to delirium (-)
Lack of social interaction.
Functional limitations (-)
Stressors that can cause or contribute to delirium (-)
Lack of natural light to help you tell day from night.

Your body and mind can keep working or recover from problems as long as you have enough functional capacity. But risk factors reduce your functional reserve. The more stressors and risk factors you have, the easier it is for delirium to happen. When stressors outweigh your functional reserve capacity — either on their own or because risk factors make you more vulnerable — you can develop delirium.

Stressors (causes and contributing factors)

The possible factors that can contribute to developing delirium in a medical setting include:

  • Conditions you have. People with dementia have a higher risk of developing delirium. Many conditions, such as cancer, infections (including HIV, pneumonia or COVID-19), sepsis or stroke can make it more likely to happen. People with a recent bone fracture are also at higher risk for developing delirium.
  • Procedures you undergo or treatments you receive. People who undergo major surgery, especially unplanned urgent or emergency surgery, have a much higher risk of developing delirium. Intubation or mechanical ventilation can also make it much more likely to happen.
  • Mobility. Not moving for extended periods, especially lying down, can affect brain function. People who move and participate in physical therapy have a lower risk of developing delirium, and delirium is shorter if they do still develop it.
  • Tethers. This term refers to anything attached to or inserted into your body that limits how you move. This includes intravenous (IV, into your vein) lines or Foley catheters (inserted devices that drain pee directly from your bladder), oxygen tubes or physical restraints. Even minor devices like a heart monitoring sensor patch can be a tether.
  • Medications you take. Some medications can increase your risk of developing delirium, even when used as prescribed. Because of this, healthcare providers often avoid prescribing certain medications to people 65 and older or those with a history of certain conditions. Polypharmacy, taking more than five medications at a time, also increases your risk.
  • Nonmedical drug or medication use. Nonmedical use of drugs, including using prescription medications in a way other than prescribed, can cause drug-induced delirium.
  • Your environment. Natural lighting helps your body maintain its sense of night and day, and losing that sense can greatly increase your risk of developing delirium. Sound is another sense that can affect your sleep/wake cycle. Lack of sleep is a significant contributor to delirium.
  • Lack of pain management. Poorly managed or unmanaged pain can contribute to your risk of having delirium.
  • Stimulation (or lack of it). Your body needs sensory input, and if you aren’t getting it, this can negatively affect your brain (especially as you get older). People who need hearing aids or eyeglasses have a higher risk of developing delirium, especially if they aren’t using these assistive items.
  • End-of-life factors. Delirium is possible during the end stages of life, especially for people receiving palliative care or hospice care.
  • Social isolation. Separation or isolation from family, friends and loved ones can worsen delirium. Family members are valued members of the treatment team and can assist in keeping you aware of your surroundings. People who have family members visiting have a lower likelihood of developing delirium and/or have fewer days where they experience delirium.

Risk factors

Several risk factors can make it easier to develop delirium. They include:

  • Age (especially 65 and older). Many changes that happen naturally as you age also increase your risk of developing delirium.
  • Dementia (or other degenerative brain diseases). Delirium can happen more easily in people who have an existing condition that affects brain functions. All degenerative and age-related brain diseases can contribute to delirium or make it more likely to happen.
  • Other chronic physical conditions. Diseases and conditions like heart disease and COPD put a strain on your body. That strain can make it easier for delirium to happen. The more chronic conditions like these that you have, the greater the strain and the higher the risk.
  • Mood disorders. A history of mood disorders, particularly depression, increases your risk of developing delirium.
  • Vision and hearing loss later in life. Your senses, especially vision and hearing, help you know what’s happening around you. Loss of those senses reduces your brain’s ability to use cues from the outside world, making it easier for delirium to develop.
  • Misuse of alcohol and nonmedical drug use. Nonmedical opioid and benzodiazepine drug use strongly increases the risk of developing delirium.
  • Previous history of delirium. People with a history of delirium are at higher risk of developing it in the future.
  • Frailty. This medical term describes how vulnerable you are to illness or injury. Frailty naturally increases as you get older. That’s why a fall for a young adult may not cause any injury, but a similar fall for someone over 65 can be more dangerous. Likewise, physical frailty makes it easier to develop delirium, especially later in life.

What are the complications of delirium?

Delirium involves widespread disruption in brain activity, which can lead to many complications. They range from minor and short-lived to severe and permanent. Complications to know about include:

  • New-onset dementia or worsening of existing dementia.
  • Falls and traumatic injuries.
  • Long-term or permanent brain function problems (cognitive impairment).
  • Inability to care for yourself, leading to a loss of independence.
  • Depression, post-traumatic stress disorder (PTSD) and other mental health conditions.
  • Loss of physical abilities.


Diagnosis and Tests

How is it diagnosed?

A healthcare provider diagnoses delirium based on a combination of methods. These include:

  • A physical exam.
  • A neurological exam.
  • Observing your behavior and any symptoms you show.
  • Talking to you and asking questions.
  • A review of your medical history.
  • Lab testing.

What tests will be done to diagnose this condition?

There aren’t any lab or diagnostic tests that can diagnose delirium directly. However, a variety of tests can play a role in searching for possible causes. These include electrolyte imbalances (such as low sodium), checking glucose (“blood sugar”) levels, or looking for signs of infection. If testing finds any causes, that can also help guide treatment.

Management and Treatment

How is delirium treated, and is there a cure?

There’s no specific treatment or medication for delirium. Instead, healthcare providers will treat causes and contributing factors they can identify. Helping people with mobility and activity or removing tethers can help delirium get better. Monitoring and adjusting medications can also help improve delirium while you undergo treatment for the underlying causes.

Medications and delirium

There aren’t any medications that treat delirium directly. Instead, medications treat underlying causes or specific delirium symptoms. That means the treatments can vary widely depending on the contributing factors and your symptoms. Healthcare providers may consider antipsychotic medications for treating hyperactive delirium because they reduce agitation and combativeness.

In general, a healthcare provider is the best person to tell you about the possible treatments they recommend (if you have a loved one who has delirium) or about the treatments you received (if you had delirium previously). The information they provide will be most relevant to your situation.

Complications/side effects of the treatment

The complications and side effects of treatment depend on the treatments used and many other factors. Your healthcare provider (or your loved one’s provider) is the best source of information about possible complications and side effects.


Is delirium preventable?

Delirium is often preventable, but most preventive measures are things only clinical personnel should do. However, family, friends and loved ones can play a very important role in reducing the risk of delirium.

Don’t try to help a loved one with delirium unless a healthcare provider (especially your loved one’s physician or nurse) tells you it’s OK to do so. Following the guidance of trained healthcare providers is key to keeping both you and your loved one safe from harm.

Healthcare provider prevention techniques

Here are some methods that healthcare providers use to prevent delirium:

  • Regular delirium assessments: Rounding and tracking mental state can help providers catch subtle warning signs that mean delirium could develop.
  • Make natural lighting a priority. Using natural light during the daytime and providing enough darkness at night help your body’s natural timing stay accurate. Staying oriented to the time of day can be a big help in preventing delirium.
  • Use glasses and hearing aids. Vision and hearing problems can increase the risk of developing delirium or make it worse. Eyeglasses and hearing aids can help your brain process information about the world around you.
  • Early mobility is key. People who move around early in treatment (with medical guidance) had a lower risk of developing delirium in large clinical trials. Your healthcare providers will tell you if this is possible for you and will help you do this safely. Following provider instructions in this area is absolutely critical to preventing injuries, especially falls. Never try to help a loved one stand up or move unless a healthcare provider tells you it’s OK for you to do so.
  • Minimize tether effects. Tethers include anything that can make it harder to move around. This includes IV and oxygen lines, urinary catheters and physical restraints. Healthcare providers will use regular “tether assessments” to minimize how these items contribute to delirium.
  • Mental exercise. Keeping your brain aware of the date, time and situation, especially with calendars and clocks, can help reduce your risk of delirium. Family members and loved ones can assist with mental exercise and stimulation with the instruction of your care provider.

How loved ones can contribute to delirium prevention.

Loved ones can play a significant role in preventing and addressing delirium for someone in a medical setting. The goal is to keep your loved one engaged and anchored to the world around them.

Things you can do include:

  • Visit. Social interactions with family, friends and other loved ones can be a major help in preventing delirium. If your loved one is in a hospital or medical facility setting, be sure to follow the rules and guidelines for visiting, too. Phone or video calls are also helpful for those who can’t make it in person.
  • Talk. Conversations that go beyond simple small talk are a fantastic way to help a loved one stay oriented. Try to engage their memory and talk about things they enjoy or find interesting. Be sure to talk to them like adults and avoid talking to them like you would a child.
  • Decorate and provide familiar objects. Setting up photos that your loved one recognizes and emotionally connects to can be a helpful way to keep them connected to their surroundings. Familiar items, like a treasured blanket or a vase with their favorite kind of flowers, may also help.
  • Engage. Participate in activities with your loved one, if possible. Board and card games, puzzles, and watching TV or listening to radio programs can all be good shared activities.

Outlook / Prognosis

What can I expect if I have delirium?

If you have delirium, the disruption in your brain function means you won’t be truly aware of or able to understand what’s happening to you. It also affects your memory, judgment and control over what you say and do.

While delirium is temporary, the effects and symptoms can sometimes linger. This is especially true when delirium is severe or goes untreated. However, even with treatment, the effects can be long-lasting. Because of that, the best way to manage delirium is to prevent it from ever happening (or at least to limit the effects).

How long delirium lasts

The duration of delirium varies, and many factors can affect it. For some, it may be a short-lived, lasting hours or days. For others, it can last weeks or even months. Even after delirium ends, some of its effects might remain for weeks, months or the rest of your life.

What’s the outlook for delirium?

The outlook for delirium can vary widely. In general, the outlook tends to be worse when delirium goes undiagnosed for long periods, or when it’s particularly severe.

Delirium can affect your physical and mental health, quality of life and your overall sense of well-being, especially when it’s severe. In more severe or long-lasting cases, delirium can cause you to develop dementia or make existing dementia worse. In the most severe cases, delirium can cause disability or significantly increase your risk of death.

Because the outlook can vary widely, your healthcare provider (or your loved one’s provider) is the best person to tell you what the outlook is for your specific situation. They can tailor that information to reflect all the positive and negative factors that play a role.

Living With

How do I take care of myself?

If you have delirium, it severely disrupts how your brain works. Having delirium means you can’t take care of yourself and have to rely on others for help. When delirium is more severe, you need higher levels of care, typically in a medical setting.

If your loved one has delirium in a medical setting, they need regular medical care. Once their delirium subsides, they may still have lingering effects. Your loved one’s healthcare provider can tell you more about those effects, what they mean, how long they’re likely to last and what kind of care or assistance your loved one will need.

Additional Common Questions

What is delirium tremens, and is it the same as delirium?

Delirium tremens (sometimes informally known as “DT” or the plural “DTs”) is a symptom of withdrawal from alcohol misuse and alcohol use disorder. It’s also known as “alcohol withdrawal delirium.”

The condition gets its name because it causes the confusion-related symptoms that make up delirium, and it also causes tremors or shakes, particularly in your hands. Delirium tremens is a dangerous symptom of alcohol withdrawal, and people who have this symptom need emergency medical care.

A note from Cleveland Clinic

If you have a loved one with delirium, it can feel scary or overwhelming to see them act confused or not like themselves. Delirium is a condition that healthcare providers are better prepared to recognize and manage. They also have a wide range of techniques they can use to try to prevent it. More importantly, you can also help prevent delirium in a loved one.

If you have questions about delirium, your healthcare provider or your loved one’s provider can give you information and guidance. They can tell you more about this condition, including what you can do to reduce the chances of developing it yourself. They can also tell you what you should and shouldn’t do to help prevent delirium in a loved one.

Medically Reviewed

Last reviewed on 02/22/2023.

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